Ambient and teleseismic elastic wavefields of the Ross Ice Shelf, Antarctica, and their application to crustal scale seismic imaging

• Main Author: Baker, Michael G.
• Other Authors: Aster, Richard C., Schutt, Derek L., Krueger, David A., Dueker, Ken G.
• Format: Text
• Language: English
• Published: Colorado State University. Libraries 2020
• Subjects: environmental seismology; seismology; ice shelves; cyroseismology; Ross Sea; Ross Ice Shelf; Antarc*; Antarctica; Ice Shelf; Ice Shelves; Sea ice
• Online Access: https://hdl.handle.net/10217/208575

2020 Spring. Includes bibliographical references. Laterally extensive floating tabular ice, such as the Ross Ice Shelf in Antarctica, is mechanically equivalent to a floating elastic plate and thus supports a variety of vibrational modes, including short-period (< 20 s) elastic waves, intermediate-to-long period (20–100 s) buoyancy-coupled elastic plate waves, and ultra long period (>100 s) gravity waves. Vibrational energy may be excited by near-field sources such as intra-shelf crevassing or the impingement of ocean gravity waves at the shelf ice front, and also by far-field sources such as teleseismic earthquake waves incident at the sub-shelf seafloor and the shelf grounded margins. Broadband seismometers deployed on an ice shelf readily observe these signals and facilitate large scale studies of ice shelf properties (via, e.g., travel-time tomography or velocity dispersion analysis) and near-field environment processes (via remote signal detection and analysis). Using two years of continuous data from a 34-station broadband seismic array deployed to the Ross Ice Shelf, Antarctica, I analyzed spatial and temporal variations in the short-to-intermediate period (0.4–25 s) ambient and teleseismic vibrational wavefields. I show that the ambient, ocean-wave-coupled wavefields are strongly modulated by sea ice concentrations in the adjacent Ross Sea, and identify three separate source processes operating in distinct period bands. Next, I show that body wave and surface wave arrivals from teleseismic earthquakes (>3000 km distant) are observed on the vertical components of ice shelf-sited seismometers with signal-to-noise ratios generally sufficient for crustal and mantle scale tomographic studies. I also show that teleseismic S-waves incident at the grounded margins routinely generate symmetric mode Lamb waves which propagate a minimum of 250 km into the ice shelf interior; this phenomenon occurs throughout the year, with broad azimuthal distribution, and may be exploited for travel-time tomography of ...